Biomass is any organic matter that is renewable over time. More simply, biomass is stored energy. During photosynthesis, plants use light from the sun’s energy (light energy) to convert carbon dioxide and water into simple sugars and oxygen.

Fossil fuels are hydrocarbon deposits, such as petroleum, coal, or natural gas, derived from organic matter from a previous geologic time. They are essentially fossilized biomass and differ from present-day biomass in that they come from organic matter created millions of years ago, which has been stored below ground.

In other words, the key difference between biomass organic matter and fossil fuels is age.

Fossil fuels contain carbon that was removed from the atmosphere, under different environmental conditions, millions of years ago.

When burned, this carbon is released back into the atmosphere. Since the carbon being released is from ancient deposits, and new fossil fuels take millions of years to form, burning fossil fuels adds more carbon to the atmosphere than is being removed.

Biomass, on the other hand, absorbs atmospheric carbon while it grows and returns it into the atmosphere when it is consumed, all in a relatively short amount of time. Because of this, biomass utilization creates a closed-loop carbon cycle.

For example, you can grow a tree over the course of ten or twenty years, cut it down, burn it, release its carbon back into the atmosphere and immediately start growing another tree in its place. With certain fast-growing biomass crops such as switchgrass, this process can occur even faster.

Wood and Agricultural Products

Biomass used today is home grown energy. Wood logs, chips, bark, and sawdust accounts for about 44 percent of biomass energy. But any organic matter can produce biomass energy. Other biomass sources can include agricultural waste products like fruit pits and corncobs.

Wood and wood waste are used to generate electricity. Much of the electricity is used by the industries making the waste; it is not distributed by utilities, it is a process called cogeneration. Paper mills and saw mills use much of their waste products to generate steam and electricity for their use.

However, since they use so much energy, they need to buy additional electricity from utilities.

Solid Waste

Burning trash turns waste into a usable form of energy. One ton (2,000 pounds) of garbage contains about as much heat energy as 500 pounds of coal. Garbage is not all biomass; perhaps half of its energy content comes from plastics, which are made from petroleum and natural gas.

Power plants that burn garbage for energy are called waste-to-energy plants. These plants generate electricity much as coal-fired plants do, except that combustible garbage—not coal—is the fuel used to fire their boilers.

Landfill and Biogas

Bacteria and fungi are not picky eaters. They eat dead plants and animals, causing them to rot or decay. A fungus on a rotting log is converting cellulose to sugars to feed itself. Although this process is slowed in a landfill, a substance called methane gas is still produced as the waste decays.

New regulations require landfills to collect methane gas for safety and environmental reasons. Methane gas is colorless and odorless, but it is not harmless. The gas can cause fires or explosions if it seeps into nearby homes and is ignited.

Landfills can collect the methane gas, purify it, and use it as fuel. Methane can also be produced using energy from agricultural and human wastes. Biogas digesters are airtight containers or pits lined with steel or bricks.

Waste put into the containers is fermented without oxygen to produce a methane-rich gas. This gas can be used to produce electricity, or for cooking and lighting.

Ethanol

Ethanol is an alcohol fuel (ethyl alcohol) made by fermenting the sugars and starches found in plants and then distilling them. Any organic material containing cellulose, starch, or sugar can be made into ethanol. The majority of the ethanol produced in the United States comes from corn.

New technologies are producing ethanol from cellulose in woody fibers from trees, grasses, and crop residues. Today nearly all of the gasoline sold in the U.S. contains around 10 percent ethanol and is known as E10.

In 2011, the U.S. Environmental Protection Agency (EPA) approved the introduction of E15 (15 percent ethanol, 85 percent gasoline) for use in passenger vehicles from model year 2001 and newer.

Fuel containing 85 percent ethanol and 15 percent gasoline (E85) qualifies as an alternative fuel. There are more than 10 million flexible fuel vehicles (FFV) on the road that can run efficiently on E85 or E10. However, just under 10 percent of these vehicles use E85 regularly.

Biodiesel

Biodiesel is a fuel made by chemically reacting alcohol with vegetable oils, animal fats, or greases, such as recycled restaurant grease. Most biodiesel today is made from soybean oil. Biodiesel is most often blended with petroleum diesel in ratios of two percent (B2), five percent (B5), or 20 percent (B20).

It can also be used as neat (pure) biodiesel (B100). Biodiesel fuels are compatible with and can be used in unmodified diesel engines with the existing fueling infrastructure.

It is one of the fastest growing transportation fuels in the U.S. Biodiesel contains virtually no sulfur, so it can reduce sulfur levels in the nation’s diesel fuel supply, even compared with today’s low sulfur fuels.

While removing sulfur from petroleum-based diesel results in poor lubrication, biodiesel is a superior lubricant and can reduce the friction of diesel fuel in blends of only one or two percent. This is an important characteristic because the Environmental Protection Agency now requires that sulfur levels in diesel fuel be 97 percent lower than they were prior to 2006.